I was reading about this fellow in America who grows these huge tomato plants which each yield hundreds of pounds of tomatoes - he's won the Guinness world record several times - but one thing he advises against is using chlorinated water to irrigate plants. Any thoughts folks?

I would agree with him. Bleach kills bacteria which includes the good stuff in the soil, it must be detrimental. However. Chlorine evaporates freely which is why swimming pools stink of it. Tap water stored in an open tank for a while would eventually be free of it. This will be indicated by the green algae growing on the sides of the tank.